Crankcase ventilations serve for the purposeful removal of gases that travel along the pistons into the interior of the crankcase. These gases are not to be released into the environment but must be supplied to the combustion process. Because they contain lubricating oil, they are conveyed to the intake valves, by which means the seats of said valves are lubricated.
By means of the connection of the intake ducts, in which vacuum prevails, to the crankcase, vacuum can be produced in the crankcase, which can lead to the introduction of contamination into the crankcase. For this reason, the pressure in the crankcase is held constant at a certain pressure by a ventilation valve.
In European Patent EP-B-0 251 159, there is described a reciprocating internal combustion engine having a ventilation device, which is provided in the form of a ventilation valve arranged at the end of the cylinder crankcase opposite the flywheel end. The ventilation valve is connected by way of tubes to the interior of the cylinder crankcase and to an oil-gas distribution line in the cylinder head. While this ventilation device is capable of functioning, it is rather costly in construction.